LetterMeLater offers one feature that your email doesn’t have, ‘the ability to schedule when an email should be sent’. It allows you to send scheduled emails without leaving your main email program, regardless whether it’s a web based service (GMail) or a desktop client (Outlook).

but I am using the site called EternityMessage.com. It was amazing. here I can send Future messages.
here i found some additional features Save online passwords and details of Wills and Trusts and send it to ur nominee in future date after u pass the life.
It was the great wonder.

This site is sending spam once you register with it!
They deny doing that but just create a new email address with an impossible name and you'll see how spam comes even to that address after you've created an account with them.

This site really is great, thanks for the tip! All the other email scheduling sites I've used always append their junk at the bottom of the emails, but there is none of that here. Also using it directly from my own email has been very handy.